The present invention relates generally to particles and in particular to stable dispersions of polymeric particles and methods for making them. In particular the present invention is directed to the manufacture of polymeric particles and stable dispersons containing same which are useful in the manufacture of paper. In addition, these materials can be tailored to function as a dry toner or a liquid developer.
Synthetic dispersions or latices are widely used today in a variety of applications extending from marking materials to paints, adhesives, paper finishing materials, and other film forming layers. In making such dispersions for use in electrostatographic marking materials, it is desirable, for example, to have a very narrow particle size distribution in the particles so as to be able to control the particle size to within and around the 8 to 10 micron range, thereby avoiding any subsequent classification step. Conventional emulsion or suspension polymer preparation techniques previously used do not allow the control of particle sizes within that size range and do not provide the narrow particle size distribution required. Typically, both emulsion and suspension polymerization start out with a monomer which is insoluble in the dispersion medium and colloidal in the case of emulsion polymerization. While the emulsion polymerization process may provide stable suspension, the particles are generally submicron in size. In contrast, with the typical suspension polymerication techniques one medium ends up being more or less uniformly dispersed or suspended in the other while the smallest particle size generally achievable is of the order of 50 to several hundred microns in diameter.